Improved measurement of brain deformation during mild acceleration using tagged MRI with a novel double trigger

Thursday, November 07, 2013 — Poster Session II
12:00 p.m. – 2:00 p.m.	FAES Academic Center (Upper-Level Terrace)	CC	BIOENG-16

Authors

AK Knutsen
E Magrath
J Zhou
R Gullapalli
JE McEntee
JL Prince
PV Bayly
JA Butman
DL Pham

Abstract

Tagged MRI is used to measure the deformation of biological tissue at high temporal and spatial resolution. Our group and collaborators have previously applied this technique to measure brain deformation in humans at non-injury level accelerations (200 rad/s2) (Sabet et al. 2008, Knutsen et al. 2012). Experimentally obtained brain deformation data in humans is important to understand and validate models of TBI. The head motion studied involves 30° rotation about a central axis before coming to a stop. The motion is repeated 18-30 times to acquire a single slice of data. Small timing differences between repetitions reduce the accuracy of computed deformation fields. The need for high repeatability makes acquiring consistent high quality data challenging in humans. To address this we implemented a novel “double trigger” system. An optical switch sends a pulse to the scanner when the subject initiates the motion. An MRI-compatible position sensor (MICRONOR, USA) sends a pulse to the scanner just prior to the stop. A tagging pulse sequence was modified so that the tag lines are applied after the first trigger and the image acquisition begins after the second trigger, which reduces temporal variations prior to the stop and improves images and deformation measurements.